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DNA is a long polymer made from repeating units called nucleotides. [6] [7] The structure of DNA is dynamic along its length, being capable of coiling into tight loops and other shapes. [8] In all species it is composed of two helical chains, bound to each other by hydrogen bonds.
The simple summary is that DNA makes RNA, and then RNA makes proteins. DNA, RNA, and proteins all consist of a repeating structure of related building blocks (nucleotides in the case of DNA and RNA, amino acids in the case of proteins). In general, they are all unbranched polymers, and so can be represented in the form of a string.
The DNA segments that carry this genetic information are called genes. Other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information. Along with RNA and proteins, DNA is one of the three major macromolecules that are essential for all known forms of life.
In mammals, key architectural proteins include: Histones: DNA is wrapped around histones to form nucleosomes, which are basic units of chromatin structure. Each nucleosome consists of 8 histone protein subunits, around which roughly 147 DNA base pairs are wrapped in 1.67 left-handed turns.
The information in DNA is held in the sequence of the repeating units along the DNA chain. [8] These units are four types of nucleotides (A, T, G and C) and the sequence of nucleotides stores information in an alphabet called the genetic code. When a gene is read by a cell the DNA sequence is copied into a very similar molecule called RNA (this ...
This nucleotide contains the five-carbon sugar deoxyribose (at center), a nucleobase called adenine (upper right), and one phosphate group (left). The deoxyribose sugar joined only to the nitrogenous base forms a Deoxyribonucleoside called deoxyadenosine, whereas the whole structure along with the phosphate group is a nucleotide, a constituent of DNA with the name deoxyadenosine monophosphate.
Basic units of chromatin structure. A nucleosome is the basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone proteins [1] and resembles thread wrapped around a spool. The nucleosome is the fundamental subunit of chromatin.
The primary structure of a biopolymer is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including stereochemistry).For a typical unbranched, un-crosslinked biopolymer (such as a molecule of a typical intracellular protein, or of DNA or RNA), the primary structure is equivalent to specifying the sequence of its monomeric subunits, such as amino ...